CN111246986A - Method for producing a component from a preform designed as a hollow body - Google Patents

Abstract

A method for manufacturing a component from a prefabricated and dimensionally stable preform, the preform being designed as a hollow body and having a preform cavity and at least one opening, the method comprising the following steps: inserting the preform (21) into a mold cavity (2) of a plastic injection molding machine mold (1) equipped with a first plastic injector; closing the mold (1); injecting a liquid plastic molding mixture of a first plastic (26) through the first plastic injector and introducing the liquid plastic molding mixture into the prefabricated cavity (23); injecting a first pressurized fluid into the liquid plastic molding mixture of the first plastic (26), forming a component cavity (28) in the plastic molding mixture by displacing the plastic molding mixture; and converting the preform (21) into the component, wherein the preform (21) is molded in a controlled manner and the outer contour of the component is formed.

Description

Method for producing components from preforms designed as hollow bodies

The invention relates to a method for producing components from preforms designed as dimensionally stable hollow bodies with at least one opening.

For example, there are several methods of producing parts from preforms in the fields of extrusion blow molding and stretch blow molding. Preforms are also called parisons. In the prescribed method, prefabricated and dimensionally stable preforms made of thermoplastic resin are introduced into blow moulds, heated under the action of compressed air and shaped into the desired parts. The mandrel can also be inserted into a heated preform, where the preform is mechanically elongated. The pressure and temperature of this method depend on the plastic used and the shape of the part. A typical pressure range is between 7 and 40 bar. A typical temperature range is between 80 and 120°C. The blow molding process is suitable for producing thin-walled parts, especially from PET, PBT, PVC, PP and PA. This includes containers such as bottles, vials or cans. However, the known blow moulding methods are not suitable for producing parts from preforms, because of the presence of plastic material, rather high pressures are required to form parts from dimensionally stable preforms.

The task of the present invention is to provide a method that enables the production of parts from prefabricated and dimensionally stable preforms, even though much higher pressures are required than blow moulding methods, in order to transform the preform into the form of the part and thus the preform Piece deformation.

This task is solved by the method according to claim 1 . The method is characterised in that a liquid plastic moulding compound is injected into a prefabricated and dimensionally stable preform and cavities are formed in the plastic moulding compound by means of a fluid injection technique. The deformation of the preform is not achieved only by heating and introduction of compressed air, as in the known blow moulding methods, but by injecting a plastic melt into the preform. The preform is designed as a hollow body and has a prefabricated cavity. When injecting the liquid plastic moulding mixture into the preform cavity and/or injecting the fluid into the liquid plastic moulding mixture, the pressure built up inside the preform is significantly higher than that of known blow moulding methods. This high pressure can also be used to transform preforms into parts with a high degree of dimensional stability, which means that large forces are required to deform the preforms. For example, they can have reinforcing structures. Based on the method of the present invention, a prefabricated and dimensionally stable preform is inserted into the mould cavity of a plastic injection moulding machine mould equipped with a first plastic syringe. The inner contour of the mold cavity substantially defines the outer contour of the part to be manufactured here. The preform is aligned with its at least one opening in the mold cavity such that the opening of the preform is adjusted to the position of the first plastic syringe in the mold. After closing the mold, a liquid plastic molding mixture of the first plastic is injected into the pre-formed cavity through a first plastic syringe. The liquid plastic molding compound here enters the preform cavity through the opening of the preform facing the first plastic syringe. The preform can have been deformed in a controlled manner so that when the liquid plastic mixture is injected into the preform, the preform adopts the outer contour defined by the cavity of the mould. The first fluid is injected under pressure into the liquid plastics molding compound, wherein cavities are formed in the plastics molding compound by displacing the plastics molding compound of the first plastic. A second pressurized fluid is injected into the cavity, wherein the first fluid is expelled from the cavity. Under the influence of the temperature and/or pressure applied to the preform by the plastic molding compound and/or the first fluid and/or the second fluid, the preform is converted into a part and adopts the part contour defined by the mold cavity. After the plastic molding compound has cured, the part is released from the mold cavity.

The first fluid and the second fluid may also be a mixture in the form of a mist or aerosol and injected into the plastic melt. If an aerosol is used for this injection technique, this is called an aerosol injection technique. If _CO2 is used as a gas, it is called _CO2 injection technique.

The introduction of the pressurized first fluid into the plastics molding mixture used as the plastics melt will cause a portion of the plastics molding mixture of the first plastic to be pressed out of the preform. At the same time, cavities are formed in the plastic molding compound. Either liquid or gas can be used as the fluid. The method of using water as the liquid is called the water injection method. The method of using gas is called the gas injection method. After the part has cooled to the specified temperature, the mold is opened and the part is removed. The next part can now be produced. The cycle starts again by filling the cavity with the preform.

Creating a cavity in the plastic molding compound of the first plastic prevents the interior of the finished part from being completely filled with plastic. The injection of the plastic melt of the first plastic causes the preform to be deformed in such a way that the profile of the preform essentially adopts the shape of the finished part. The subsequently introduced first fluid creates a cavity inside the part, so that the finished part has the form of a cavity. If a solid part is to be produced from a preform completely filled with the first plastic, the introduction of the first and second fluids is not necessary.

When the plastic molding compound is injected into the preform, the preform cavity can be partially or completely filled with the plastic molding compound. Preferably, the preform cavity is completely filled with the plastic moulding compound during the injection process so as to build up the pressure required to deform the preform. When the first fluid is introduced, it is noted that a portion of the plastic molding compound is forced out of the preform cavity of the preform. For this purpose, the preform should preferably have additional openings through which excess plastic molding compound of the first plastic can escape from the preform. Here, the first opening of the preform serves as an inlet for the plastic molding compound, while the other opening of the preform serves as an outlet for excess plastic molding compound. In this case, the mold is also specially designed in order to discharge excess plastic molding compound. The excess plastic molding compound can be fed back into a plastic syringe, for example, so that it can be used for another cycle. These types of methods are called melt pushback processes.

If high pressure or high temperature is not required to deform the preform, it is sufficient to only partially fill the preform cavity during injection of the plastic molding compound. In this case, the first fluid ensures the distribution of the plastic molding compound in the prefabricated cavity.

In particular, injecting the plastic molding compound and/or displacing the plastic molding compound with the first fluid results in such high pressures that, if the preform has a high dimensional stability, a targeted deformation of the preform is even triggered. The introduction of the plastic molding compound and/or the first fluid is primarily used to build up pressure. Plastic molding compounds can also be used to shape parts and mold additional parts onto preforms.

In particular, the pressure built up during the injection of the liquid plastic melt of the first plastic can be many times greater than the pressure normally used for blow molding.

The finished part has, in addition to the preform on its inner side adjoining the cavity, a layer made of the first plastic. This can be taken into account when producing prefabs. The wall thickness of the preform can be reduced accordingly.

The exterior of the finished part is formed from a preform that is deformed in a controlled manner, with the exception of possible additional moulded parts.

The introduction of the first fluid and the second fluid may be organized such that the plastic molding compound is uniformly distributed. Furthermore, the introduction of the first fluid and the second fluid can also be carried out in a controlled manner such that the plastic moulding compound builds up especially at the location of the preform where the material weakens when moulded into a part. If the thickness of the wall of the preform is partially reduced during forming, more of the plastic moulding compound of the first plastic can be accurately placed in this section than in other sections.

With the method according to the invention, it is possible to increase the diameter in one or more sections on a preform having a cylindrical elongated shape, and thereby widen the outer contour. In this way, the part will have sections of different sizes in cross section.

If forming the preform into a part results in a contraction in length, in particular due to expansion of the parts, the mould may be equipped with replaceably mounted parts. In this way, the mold can shrink with the length of the preform.

With the method according to the invention, it is possible, for example, to manufacture pipelines for conducting media. These types of lines conduct media such as liquids or gases, especially water, oil or air. Depending on the field of use, these lines must be particularly stable and have sections with different cross-sections. High stability is achieved through the use of suitable prefabricated parts, with reinforcement structures if necessary. By injection of the first plastic according to the invention, the preform is deformed in a controlled manner such that the finished part has a profile defined by the cavity of the mould and an open cross-section defined by the fluid injection technique.

According to an advantageous embodiment, the preform is made at least partially from plastic, ie from the second plastic. For example, PET, PBT, PVC, PP and PA are suitable as second plastics. As far as PA is concerned, PA6, PA6.6 and PA12 are particularly suitable.

According to another advantageous embodiment of the invention, the first plastic and the second plastic are different. In addition to the shaping of the part, by using a different plastic, parts of a first plastic that is different from the second plastic of the preform can be moulded onto the part.

According to another advantageous embodiment of the invention, the first plastic and the second plastic are identical.

According to another advantageous embodiment of the invention, a prefabricated and dimensionally stable preform is inserted into a mould cavity with a plastic strip structure as reinforcement. This is also called compounding. Here, the plastic belts are processed into woven fabrics, nets or braids. It could also be packaging material. Plastic belts can be reinforced with carbon fiber or glass fiber. The reinforcement may alternatively or additionally be made of PPTA (trade name Kevlar). Furthermore, reinforcements in the form of natural fibers or organic fibers are also possible. If the preform is made of a second plastic, the plastic strip structure can be embedded in the second plastic of the preform, so that the prefabricated and dimensionally stable preform is integral. Alternatively, the plastic band structure may be arranged loosely on the surface of the preform. The plastic tape structure can be made from one or more layers of plastic tape. The plastic strip structure can be embedded in the second plastic of the preform in such a way that it does not protrude beyond the surface of the preform. Alternatively, the plastic belt structure is located on the outside of the preform. The plastic belt structure can also be located inside the preform. Pipes with this plastic belt structure are also called belt pipes. With the method according to the invention, preforms with plastic strip structures can be partially or completely widened.

According to another advantageous embodiment of the invention, the plastic strip structure is embedded in the second plastic.

According to a further advantageous embodiment of the invention, the preform consists at least partially of metal.

According to another advantageous embodiment of the invention, the preform inserted into the mould cavity has at least a second opening. The cavity of the mold has a cavity portion that engages the second opening of the preform when the preform is inserted into the cavity. When the pressurized first fluid is injected into the liquid plastic molding compound of the first plastic, the plastic molding compound is extruded through the second opening of the preform to be forced into the cavity portion and at least partially fill the cavity part. As a result, an additional part made of the first plastic can be moulded onto the preform and thus onto the part. These additional parts are only made of the first plastic, and not the material layers of the preform and the first plastic layer like the rest of the part.

According to another advantageous embodiment of the invention, a cavity is formed in the plastics moulding mixture contained in the moulding cavity part by injecting the first fluid into the plastics moulding mixture which is pressed into the moulding cavity part. The part made of the first plastic and moulded on the part is designed to be hollow inside.

According to a further advantageous embodiment of the invention, the plastics molding compound containing the reinforcing fibers is injected as a liquid plastics molding compound of the first plastic. These can be glass fibers, carbon fibers, aramid fibers, natural fibers or other additives. Glass fiber reinforced plastic is also known as GRP. Carbon fiber reinforced plastic is also known as CRP. During injection into the preform cavity, reinforcing fibers accumulate inside the preform. They thus reduce the risk of preforms with reinforcing structures that, when the second plastic is injected into the preform at high pressure, the first plastic will tear in the spaces between the individual fibers forming the reinforcing structure.

According to another advantageous embodiment of the invention, the preform is made of several layers of plastic which are filled with reinforcing fibers to different degrees.

According to another advantageous embodiment of the invention, several layers of first, third or other plastics are injected into the preform. Plastics can be filled with different amounts of different reinforcing fibers. When the third plastic is injected, the first plastic can be displaced out of the prefabricated cavity. Targeted displacement of the preform can occur with each injected plastic. It depends on the set pressure in each case. In this case, the finished part may have multiple layers of different plastics. This is called multiple layers.

According to another advantageous embodiment of the invention, the preform is preheated before the plastic moulding mixture of the first plastic is injected into the preform. If the preform is preheated, the first plastic of the injected plastic molding compound can better engage with the second plastic of the preform, if the preform is made of plastic. If the preform is made of metal, preheating of the preform is usually not required.

According to another advantageous embodiment of the invention, the mould is heated before injection of the plastic moulding mixture, whereby the preform is preheated in the mould cavity.

According to another advantageous embodiment of the invention, a third heating fluid is introduced into the preform before the injection of the plastic moulding mixture. The preform is preheated by this third fluid.

According to a further advantageous embodiment of the invention, a second plastic syringe provided on the mold is used for externally molding a liquid plastic molding mixture of a third plastic onto the preform. Therefore, the plastic molding compound of the third plastic does not accumulate on the inside of the preform, but only on the outside. This leads to other design possibilities for components. By injecting the plastic molding compound of the third plastic, it must be ensured that the preform does not collapse in the mold. In this way, the pressure can be set accordingly.

According to a further advantageous embodiment of the invention, after the injection of the liquid plastic moulding mixture of the first plastic, the liquid plastic moulding mixture of the third plastic is injected into the mould.

According to a further advantageous embodiment of the invention, the liquid plastic molding mixture of the third plastic is injected into the mold before the liquid plastic molding mixture of the first plastic is injected.

According to another advantageous embodiment of the invention, the third plastic material is different from the first plastic material. The third plastic can also be different from the second plastic.

According to another advantageous embodiment of the invention, the third plastic corresponds to the first plastic. In particular, the third plastic can also correspond to the second plastic.

According to a further advantageous embodiment of the invention, the liquid plastic moulding mixture of the first plastic is first injected into the prefabrication cavity at a first pressure p ₁ until the prefabrication cavity is filled with the liquid plastic moulding mixture of the first plastic. Do volume filling. The injection of the liquid plastic molding mixture of the first plastic is then continued at a second pressure p ₂ , where p ₂ >p ₁ , and the preform is converted into a component. The pressure _p2 can be many times greater _than the pressure p1. This depends on the material of the preform and whether the preform is equipped with additional reinforcements. If the preform is made of a second plastic without reinforcement, _p2 is generally smaller than a preform made of the second plastic without reinforcement. The _p2 is even higher for preforms made of metal. Due to the high pressure, the deformation of the preform to the component is triggered or at least facilitated.

According to another advantageous embodiment of the invention, p ₂ is at least twice as large as p ₁ .

According to another advantageous embodiment of the invention, p ₂ is at least 10 times greater than p ₁ : p ₂ =10*p ₁ , preferably at least 50 times greater than p ₁ p ₂ =50*p 1 , particularly preferably at least p ₁ 70 times: p ₂ =70*p ₁ .

According to another advantageous embodiment of the invention, p ₁ is about 60 bar and p ₂ is about 4000 bar.

Further advantages and advantageous embodiments of the invention can be obtained from the following description, the drawings and the claims.

Description of drawings

The drawings illustrate typical embodiments of the inventive subject matter. In the attached image:

Figure 1 shows a mold with a cavity, two injection heads and a needle valve;

Figure 2 shows a preform made of a second plastic in longitudinal section;

Figure 3 shows a mould cavity with the injection head according to Figure 1 and a preform inserted into the mould cavity;

Fig. 4 shows a mould cavity with the preform according to Fig. 3, wherein two injection heads are inserted into the preform;

Figure 5 shows a mould cavity with the preform according to Figure 3 and a melt of the first plastic injected into the preform;

Figure 6 shows the cavity with the preform after further injection of the melt of the first plastic with increasing pressure;

Figure 7 shows a mold cavity with a preform and a melt of a third plastic injected into the preform;

Figure 8 shows the mold cavity with the preform and the first and third injected plastic after the cavity is created using water.

Detailed ways

FIG. 1 shows a mold 1 with a mold cavity 2 with a first injection head 3 and a second injection head 4 . The mold is part of an injection molding machine not otherwise shown in the figures. Each injection head 3 , 4 is equipped with a drive, not shown in the figures, which actively moves the two injection heads 3 , 4 into and out of the mould cavity 2 . The mold cavity 2 is elongated. When moving in the longitudinal direction of the mould cavity, the two injection heads 3 , 4 move relative to each other when entering the mould cavity 2 and move away from each other when moving out of the mould cavity 2 . According to the illustration in FIG. 1 , the two injection heads 3 , 4 are moved out of the mold cavity 2 by means of a drive. The first injection head 3 is also movably mounted on the guide rails 5 , 6 . The melts of two different plastics are injected into the mould cavity 2 through a total of four needle valves 7 , 8 , 9 , 10 . Furthermore, the fluid is injected into the liquid melt through the needle valve 10 to create the cavity.

Cavity 2 has three cavity sections:

The first cavity portion 11 is elongated. It has regions 12, 13 which are designed cylindrically with a circular cross-section. In regions 14 , 15 the opening cross-section is larger than in regions 12 , 13 .

The second cavity part 16 takes the form of an attachment on the first cavity part.

The third cavity part 17 has a cylindrical ring 18 and two appendages 19 , 20 which protrude to one side around the cylindrical area 12 . The second and third cavity parts 16, 17 can be separated from the first cavity part by means of sliders. The sliders are not shown in the figure. During execution of the method on the preform inserted into the cavity 2 , the slide blocks prevent the second 16 and third 17 cavity parts from being deformed in the same way as the regions 14 , 15 of the first cavity part 11 .

FIG. 2 shows the preform 21 in longitudinal section. The preform 21 takes the form of a dimensionally stable elongated tube with a circular cross-section. The preform 21 has a housing 22 adjoining the preform cavity 23 . The housing 22 is made of a second plastic in which is embedded a reinforcing structure made of plastic strips, which is not shown in the figures. The preform has openings 24, 25 on each end.

The view according to FIG. 3 shows the insertion of the preform 21 into the mold cavity 2 . The preform 21 is centered by the ends of the injection heads 3 and 4 towards the cavity 2 . The outer contour of the preform 21 corresponds in section to the inner contour of the mold cavity 2 . This is especially true for the cylindrical regions 12 and 13 of the first cavity part 11 .

The view according to FIG. 4 shows that the injection heads 3 and 4 both protrude into the mould cavity 2 by means of a drive not shown in the figure. The parts of the injection heads 3 and 4 facing the mould cavity 2 are now integrated into the preform cavity 23 of the preform 21 .

In the next step, as shown in FIG. 5 , the needle valve 10 is used to inject the liquid melt of the first plastic 26 into the prefabricated cavity 23 . For this purpose, the preform 21 has a through hole at the location of the needle valve 9 (not shown in the figures). The first plastic 26 is injected into the preform 21 at a given first pressure p ₁ and a given first temperature T ₁ until the entire preform cavity 23 of the preform 21 is filled with the melt of the first plastic 26 .

As shown in FIG. 6 , the injection of the liquid melt of the first plastic 26 is then continued through the needle valve 10 at a second pressure p ₂ greater than the first pressure p ₁ . The pressure p ₂ is so high that the preform 21 deforms in the regions 14 , 15 of the first cavity part 11 so that the preform assumes the shape of the cavity in the regions 14 , 15 . However, this is not the case in the second cavity portion 16 and the third cavity portion 17 . Deformations in the second and third cavity parts 16, 17 are prevented by slides not shown in the figures. During the deformation of the preform 21 in regions 14 and 15, the axial length of the preform 21 is shortened. Since the injection head 3 is movably mounted on the rails 5, 6, it can follow this shortening. The injection head 3 is here moved along the rails 5 , 6 in the direction of the injection head 4 by a distance corresponding to the axial shortening of the preform 21 .

Slides in the form of profiled slides are then moved in the cavity parts 16 and 17 so as to connect the corresponding parts of the cavity to the first cavity part 11 . As shown in FIG. 7 , the liquid melt of the third plastic 27 is now injected into the second and third cavity parts 16 , 17 using the needle valves 8 and 9 . Since the preform 21 is still filled with the liquid melt of the first plastic 26 , when the third plastic 27 is injected, the preform 21 does not deform in the second and third cavity parts 16 , 17 .

In the process step shown in FIG. 8 , the needle valve 9 is used to inject pressurized water into the liquid melt of the first plastic 26 . A part of the liquid melt of the first plastic material 26 is displaced from the preform 21 and is pressed out of the mold cavity 2 through the opened needle valve 7 . A component cavity 28 is formed in the liquid melt of the first plastic in the prefabrication cavity 23 . As can be seen in the figures, the deformed preform has a first plastic 26 on the inside and a moulded part of the third plastic 27 in the second and third cavity parts 16 , 17 on the outside. The parts of the finished part defined by the second and third cavity parts 16, 17 of the cavity 2 are attachment points.

The mold cavity can then be opened and the part removed.

All features of the invention may be essential to the invention individually or in any combination.

reference number

1 mold

2 Cavities

3 injection heads

4 injection heads

5 rails

6 rails

7 Needle valve

8 needle valve

9 Needle valve

10 Needle valve

11 The first cavity part

12 Cylindrical area

13 Cylindrical area

14 Regions

15 Regions

16 Second cavity part

17 The third cavity part

18 Ring area

19 Accessories

20 Accessories

21 Prefabs

22 shell

23 Prefabricated cavities

24 openings

25 openings

26 First Plastic

27 Third plastic

28 Component cavity

Claims (20)

1. A method for producing a component from a prefabricated and dimensionally stable preform, which is designed as a hollow body and has a preform cavity and at least one opening, comprising the following process steps:

inserting the preform (21) into a mold cavity (2) of a plastic injection molding machine mold (1) equipped with a first plastic injector, wherein an inner contour of the mold cavity (2) substantially defines an outer contour of the component,

aligning the preform (21) in the mould cavity (2) to adjust the opening of the preform (21) to the position of the first plastic injector in the mould (1),

closing the mould (1),

injecting a liquid plastic molding compound of a first plastic (26) by means of the first plastic injector and introducing the liquid plastic molding compound into the preform cavity (23) through an opening of the preform (21) facing the first plastic injector,

injecting a first pressurized fluid into a liquid plastic molding compound of the first plastic (26), wherein a part cavity (28) is formed in the plastic molding compound by displacing the plastic molding compound,

injecting a second pressurized fluid into the component cavity (28), wherein the first fluid is displaced from the component cavity (28),

transforming the preform (21) into the component, wherein the preform (21) is molded in a controllable manner and the outer contour of the component is formed by means of the pressure and/or the temperature acting on the preform (21) by means of the plastic molding compound of the first plastic (26) and/or the first fluid and/or the second fluid,

curing the plastic molding compound of the first plastic (26),

-demoulding the part from the mould cavity (2).

2. Method according to claim 1, characterized in that the preform (21) is at least partly composed of a second plastic.

3. The method of claim 2, wherein the second plastic is different from the first plastic (26).

4. The method of claim 2, wherein the first plastic (26) and the second plastic are the same.

5. A method according to any one of claims 2-4, characterized in that a prefabricated and dimensionally stable preform (21) is inserted into the mould cavity (2), which comprises a plastic band structure in the form of a packaging material, a woven fabric, a net or a braid made of plastic band.

6. A method as claimed in claim 5, characterised in that said plastic belt structure is embedded in a second plastic of said preform (21).

7. Method according to any of the preceding claims, characterized in that the preform (21) is at least partially made of metal.

8. Method according to any of the preceding claims, characterized in that the preform (21) inserted into the mould cavity (2) has at least a second opening, the mould cavity (2) having a mould cavity part, which mould cavity part engages with the second opening of the preform (21) when the preform (21) is inserted into the mould cavity (2), the pressurized first fluid being injected into the liquid plastic moulding mixture of the first plastic, which plastic moulding mixture is pressed through the second opening of the preform to be pressed into the mould cavity part and to at least partly fill the mould cavity part.

9. The method of claim 8, wherein a cavity is formed in the plastic molding compound contained in the mold cavity portion by injecting the first fluid into the plastic molding compound of the first plastic (26) that is pressed into the mold cavity portion.

10. Method according to any one of the preceding claims, characterized in that a plastic molding compound containing reinforcing fibers is injected as the liquid plastic molding compound of the first plastic (26).

11. Method according to any one of the preceding claims, characterized in that the preform (21) is preheated before the injection of the plastic molding compound of the first plastic (26) into the preform (21).

12. Method according to claim 11, characterized in that the mould (1) is heated to preheat the preform (21) in the mould cavity (2).

13. A method according to claim 11 or 12, characterized in that a third heating fluid is introduced into the preform (21), which third heating fluid preheats the preform (21).

14. Method according to any one of the preceding claims, characterized in that a second plastic injector arranged on the mould (1) is used for moulding a liquid plastic moulding compound of a third plastic onto the preform from the outside.

15. Method according to claim 14, characterized in that after the injection of the liquid plastic molding compound of the first plastic (26), a liquid plastic molding compound of the third plastic (27) is injected into the mold (1).

16. Method according to claim 14, characterized in that a liquid plastic molding compound of the third plastic (27) is injected into the mold (1) before the injection of the liquid plastic molding compound of the first plastic (26).

17. Method according to any one of claims 14 to 16, characterized in that the third plastic (27) is different from the first plastic (26).

18. Method according to any one of claims 14 to 16, characterized in that the third plastic (27) corresponds to the first plastic (26).

19. Method according to any of the preceding claims, characterized in that in the pre-chamber (23) first a first pressure p is applied₁Injecting the liquid plastic molding compound of the first plastic (26) until the pre-cavity (23) is filled with the liquid plastic molding compound of the first plastic (26), and then at a second pressure p₂Continuing to inject a liquid plastic molding compound of the first plastic (26), wherein p₂>p₁Wherein the preform (21) is converted into the component.

20. The method of claim 19, wherein p is₂Ratio p₁At least two times larger, preferably at least ten times larger, particularly preferably at least fifty times larger.

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